In general, a camera is designed to use films equal in width. However, some cameras using "Brownie" type films are designed so that they can be able to use both a Brownie film (120 film and 220 film) and a 70 mm film. In this case, the cameras should be of a so-called "film back change type", because of the following reasons:
(i) The width of the leader paper of the 120 film is about 63 mm, and that of the 70 mm film is 70 mm. Accordingly, in ordinary cases, it is impossible to commonly use the mechanism adapted to maintain the film flat for both of the films.
(ii) The spool (about 25.4 mm.sup..phi. .times.66 mm.sup.h) of the Brownie type film is much smaller in size than the magazine (about 41 mm.sup..phi. .times.76 mm.sup.h in the case of a 15 ft. roll) of the 70 mm film. Accordingly, the space occupied by the film accommodating section in the camera is necessarily sized for the 70 mm film, which results in an increase of the size of the camera.
The above-described film back exchange type camera is advantageous in that the film can be exchanged under ambient light conditions, but it is still disadvantageous in the following areas:
(1) Since the rail surface is on the side of the exchange back, it is necessary to precisely maintain the relationship between the camera and the exchange back.
(2) For the shutter on the side of the camera body and/or the film on the side of the film exchange back, it is necessary to provide a security measure when coupled prior to winding.
(3) Because it is necessary and required to provide a counter mechanism on the side of the film exhchange back, the control and cooperation of the shutter winding mechanism and the release mechanism on the side of the camera body become intricate. In addition, a counter mechanism must be provided in each film exchange back.
(4) It is required to provide a movable light intercepting member for the film exchange back. It is necessary to provide security means so that the film exchange back itself is not exposed to light or the film is not exposed to light erroneously as the case may be and that it can be loaded in the camera without being exposed to light.
Accordingly, the cost of such a camera is greatly increased; that is, the camera is necessarily expensive.
In order to reduce the cost of the camera, a method has been considered in which the camera body is integral with the film exchange back (in this case, the advantages and disadvantages thereof are the reverse of those of the above-described back exchange type camera). If, in this case, the camera is intended to commonly use the Brownie film and 70 mm film, then as was described the space of the film accommodating section in the camera is determined for the 70 mm film, and therefore the size of the camera is necessarily increased. At present, Brownie type films are used much more frequently than 70 mm films. Therefore, such a large size camera is lower in commercialization potential, although it may be suitable for the picture taking case where it is required to take as many as possible without exchanging the film. Accordingly, heretofore, no 70 mm film is useable for the camera which uses a Brownie type film and carries out no film back exchange.
On the other hand, in a camera in which a Brownie type film is loaded behind the picture plane, the film path is in the form of a Greek character omega ".OMEGA.". Accordingly, in order to facilitate film loading, such a camera is, in general, designed so that it is provided with a reel having means for mounting the spool of a Brownie film and means for guiding and holding the film, and the reel is detachably mounted in the reel accommodating chamber in the camera.